This invention relates in general to engine shrouds for gas turbine engines and, more specifically, to an improved shroud having integral corners.
Ducted fan jet engines for aircraft applications have come into widespread use. Such engines include a core engine within a streamlined shroud, a stage of fan blades mounted upstream of the engine and driven thereby, and a nacelle surrounding the fan blades and shroud and spaced from the shroud to provide a bypass duct between nacelle and shroud through which compressed air is forced by the fan blades.
The shroud which surrounds the engine and forms both the housing for the engine and the interior wall of the bypass duct is often formed from two halves which are fastened together to form the shroud. This arrangement facilitates engine servicing, removal and reinstallation. Each shroud half consists of a center section having a generally semicircular cross-section which forms half of the tubular shroud around the engiee and two radially extending flanges attached to the edges of the each center section to aid in supporting the shroud within the engine casing and nacelle and to carry means for securing the shroud halves together.
The intersection between flanges and center section is a rather sharp corner, which could not be formed directly in the generally used shroud materials. The shroud is ordinarily fabricated from a panel which comprises a honeycomb core to which two face sheets are bonded. The panel is generally formed from a metal such as aluminum or high strength fiber reinforced resin matrix materials such as graphite fibers in an epoxy resin matrix. The corners between flanges and center section have in the past been made by fastening separate panels together with a variety of clamping and fastening fixtures.
While the prior corner fasteners have been effective, they are cumbersome, heavy, require considerable skill to install and are more expensive and less reliable than a continuous integral panel would be. Thus, there is a continuing need by for shrouds formed as a continuous panel, eliminating corner fittings.